Liquid Flow Behavior And Mixing Characteristics In Rotating Bar Reactor

Rotating bar reactor(RBR)is a novel device for process intensification,which is mainly composed of inner rotating shaft and outer shell.The rotation of the shaft can generate disturbance to the liquid flow in the gap between rotating shaft and shell,which can further intensify the fluid flow,mixing and other processes in the reactor.The fluid flow and mixing characteristics in the reactor have an important influence on reactor scale-up,particle size and molecular weight distribution,product quality,etc.,thus this becomes an important topic in reactor research.This thesis focuses on the basic research of the fluid flow and mixing characteristics in a novel RBR.Firstly,the residence time distribution(RTD)of the liquid in the RBR was studied using the pulse method,and the influence of feeding method,rotational speed,flow rate on the RTD of liquid was investigated.Then,the micromixing performance of the RBR under different operating conditions was explored using the iodide-iodate parallel competition reaction system,and the micromixing characteristic time was calculated using the incorporation model based on experiments.In the end,the macromixing performance in the reactor was further researched using the computational fluid dynamics simulation method.The results showed that the changes in operating conditions had a consistent effect on both macromixing and micromixing.The research results are as follows:(1)The degree of backmixing of the fluid in the RBR increased with the increase of liquid flow rate,meaning that the fluid flow developed toward full flow when the flow rate increased.The influence of the rotational speed on the fluid backmixing in the reactor was a slight change trend that decreased first and then increased.At the speed of 1000 rpm,the fluid in the reactor is backmixed to a minimum and the dispersion is minimal.(2)In the micromixing experiments,the micromixing performance was better when the main solution was tangentially fed.Increasing the rotational speed of the RBR and the fluid flow rate would make the segregation index decrease and improve the micromixing performance.When the viscosity of the system,the hydrogen ion concentration and the volumetric flow ratio of the two solutions were increased,the segregation index obtained from experiments would obviously increase,meaning that the micromixing performance deteriorated.Based on the incorporation model,the micromixing characteristic time of the RBR was calculated to be 10-6～10-5s.Compared with other reactors,it showed that the RBR had excellent micromixing performance.(3)The computational fluid dynamics was used to qualitatively and quantitatively study the macromixing performance in the RBR.The results showed that when the feeding method was tangentially feeding,increasing the rotational speed and the liquid flow rate can both make the segregation intensity smaller and the macromixing performance better.